Principal Usha Mehta, the teacher and a servant had tasted the food, which was cooked by an NGO. Soon after, their faces started swelling. They were rushed to Brahm Shakti Hospital from where they were referred to Max hospital.

Azad Singh, mayor of North Delhi Municipal Corporation, said the incident was under investigation.

Twenty-three students of a government school had died in Bihar's Saran district July 16 after eating a mid-day meal that was poisoned with a chemical used in insecticides.

Soon after the tragedy, Bihar Chief Minister Nitish Kumar instructed principals and cooks in every school to first taste the mid-day meal before it is served to children.